Carbon Dioxide Characterization of Carbons with the TriStar II 3020

Introduction The use of carbon dioxide allows for rapid, high-resolution characterization of microporous materials. The Micromeritics TriStar II 3020 can be used to characterize micropores below 10 angstroms within 8 hours using CO2 as the adsorptive gas and an ice bath (273 K) for the analysis bath. Isotherms from CO2 adsorption were compared with N2 […]

The Surface Area of Magnesium Stearate — An Excipient Used In Pharmaceuticals

Magnesium stearate is widely used in the pharmaceutical industry as an excipient in tableted drugs. The physical properties of the magnesium stearate influence the tableting characteristics of the formulation as well as the in vivo degradation and dissolution of the solid drug. The United States Pharmacopia, which has already established a standard for the particle […]

Liquid Nitrogen Level When Using Isothermal Jackets

When isothermal jackets are used, it is important not to overfill the liquid nitrogen in the Dewar. At the start of an analysis, the liquid nitrogen level should be no higher than 1/4 in. (0.64 cm) from the top of the isothermal jacket. Overfilling overrides the function of the isothermal jacket and prevents effective control […]

Can I Calculate Density From Free Space

A frequent question is often posed by users, can density be calculated from free space measured on a gas adsorption analyzer instead of using an instrument that is designed to obtain density? This tech note will explore the possibility of using such a method and compare with results obtained by the Micromeritics AccuPyc II. Gas […]

Expanding the Material Characterization “Toolbox” for Excipient and Active Pharmaceutical Ingredient (API) Vendor Qualification

Physical characterization of pharmaceutical excipients is not only a requirement but can also provide data that can be predictive in nature regarding the performance of final dosage forms including tablets, capsules, inhaled dosage forms, transdermals, and others. Manufacturers generally provide some of this physical testing data, such as particle size. In the case of particle […]

Degas Backfill Gas Selection for Micromeritics Gas Adsorption Instruments

Introduction Specific surface areas and pore volume distributions are often determined using gas adsorption techniques. Prior to analysis, any adsorbed gas or vapor phase (such as water or other volatiles) should be removed from the sample. This process is often referred to as degassing the sample. Degassing usually involves either heating the sample or flowing […]

Measuring the Isosteric Heat of Adsorption of CO2 on Micro-Porous Carbons

This application note details the method for obtaining the isosteric heat of adsorption of CO2 on a range of adsorbent grade activated carbons. CO2 adsorption isotherms below saturation vapor pressure were collected using a Micromeritics® 3Flex Surface Analyzer equipped with an iso-controller unit for temperature control. Isosteric heat of adsorption is calculated across the fullest […]

Calculating Free Space with Micromeritics Static (Manometric) Adsorption Instruments

Introduction Specific Surface Area and the Pore Volume Distribution of materials are frequently determined from the adsorption isotherm, which is the quantity of gas that is adsorbed onto the surface and within the pores of a material as a function of pressure above the sample. These analyses are frequently conducted at cryogenic temperatures to enhance […]

Characterization of Carbons Using a Micromeritics 3Flex

Dr. Darren Lapham, MCA Services, Cambridgeshire, UK. This application note describes the analysis of full gas adsorption / desorption isotherms of carbon black samples using a Micromeritics 3Flex micropore instrument. From the isotherms, BET surface area together with micro-pore, meso-pore and small macro-pore size distributions can be ascertained along with pore volume and pore area. […]

Adding a Custom Model to the NLDFT Library – A CO2 GCMC Model for Carbons

New models for determining the pore volume and pore size distribution of porous solids may be easily added to MicroActive™. These kernels developed using NLDFT, GCMC and other variants have been available for more than 20 years. Traditionally instrument manufacturers have supplied these proprietary models. To introduce new powerful capabilities for users, Micromeritics has developed […]